1. Field of the Invention
The present invention relates to an apparatus and method for inspecting defects, such as foreign substances, flaws, dirt, and other contamination, that are present on a desired surface of a sample such as a semiconductor wafer (hereinafter, referred to simply as a wafer).
2. Description of the Related Art
In recent years, higher-density integration of semiconductor integrated circuit (IC) devices and finer structuring of circuit patterns have progressed. Today, circuit patterns with line widths less than 1 μm are coming to be manufactured. To manufacture these fine-structured ICs at a high yield ratio, it is essential to appropriately manage manufacturing processes by detecting wafer surface defects and inspect the sizes and shapes of the defects or quantitatively examine the degree of cleanliness of various semiconductor-manufacturing apparatuses and processes. At wafer manufacturers and IC-manufacturing factories, therefore, wafer defect inspections with a defect inspection apparatus have traditionally been conducted for appropriate management of the manufacturing processes.
Defect inspection apparatuses of this kind are broadly divided into two types according to inspection scheme. One type is a data comparison type of defect inspection apparatus adapted to compare a bright-field data based on vertical downward illumination, and a previously stored standard pattern. The other type is a defect inspection apparatus that uses such dark-field data as described in, for example, JP-A-11-51622. In the latter type, the light scattered under a dark field of oblique illumination is detected and the existence, position coordinates, and number of defects are recognized from the coordinates of the section estimated as the source of occurrence of the scattered light, or from the intensity of the scattered light.